Caption: A laboratory chemostat containing a culture of Escherichia coli, genetically modified to produce the bioplastic, polyhydroxybutyrate (PHB). PHB is a non-toxic biodegradable plastic suitable for use as food packaging, plastic cutlery and drinking vessels. E. coli is a fast growing bacterium suited to bulk liquid culture. It does not naturally make PHB. Genetic modification is used to control the amount and type of PHB produced by E. coli in culture. The picture shows a research-scale chemostat containing E. coli into which have genes for PHB synthesis inserted. At and above the liquid culture surface, the plastic can be seen adhering to the inside of the chemostat (off-white strands, centre and to left). PHB is expensive compared to oil-based plastics. Current research concerns the possible use of waste water as a feedstock in order to increase the competitiveness of the product.